The present invention relates to sonobuoys, and more particularly to an air-dropped sonobuoy having a quick and reliable means for jettisoning a drag chute deployed in the air, and for releasing component parts contained within the sonobuoy housing for deployment in the water.
In the evolution of air-dropped sonobuoys towards smaller configurations, improved deployment devices are needed to sustain for increase reliability of automatic deployment systems while minimizing costs and space requirements. A typical air-launched sonobuoy deploys a drag chute after ejection from an aircraft launcher to retard and stabilize its descent. Upon reaching the sea, the chute is jettisoned and the sonobuoy further deployed into an operating mode wherein a hydrophone is suspended at a preselected depth from a radio-transmitter supported at the surface by a flotation device. The chute is usually jettisoned by a release mechanism actuated in response to a signal indicative of the sonobuoy's immersion in the water. For example, a water-activated or impact switch triggers a mechanism which jettisons the chute. Prior art release mechanism have been costly, too large or unreliable. Reliability has been particularly problemmatical in release under very high load conditions such as occurs after the sonobuoy enters the water with the open canopy. A sudden and greatly increased drag force is produced just at the time release is desired. Due to these high forces, release mechanisms of the prior art have often failed to function preventing the sonobuoy from complete operational deployment. More sophisticated release mechanisms usually occupy too much of the precious space within the sonobuoy housing.